One common piece of heavy equipment used to produce hydrocarbons from the earth is referred to as: a workover rig, a completion rig, or a pulling unit. Such a thing can do many tasks, but it is primarily used to hoist damaged tubing from a well and lower undamaged tubing into a well so that oil and gas can flow more freely. A workover rig can also be used to “complete,” repair, or swab a well to maximize its rate of fluid production.
A workover rig comprises a truck carrying a telescoping mast and a winch. In use, the truck is backed up to a well, the mast is raised, and the lifting of tubing is initiated using the winch. A typical, workover rig is used only during daylight hours. A workover rig cannot drill into the earth unless equipped with a special “power swivel” that moves up and down while turning drill pipe extending into the well.
Thousands of men in the United States work upon workover rigs and are interested in workover rigs. It is believed that many would like to own a functioning model of such a rig. Duplicating every feature of a workover rig in a mass-produced model, however, is not practical since many features would be tiny and especially costly to make. Changes are necessary in the various apparatus that: pivots the mast to its substantially perpendicular, upright orientation, telescopes the mast to its full length, and hoists tubing.